Immune complexes from patients are being detected and studied by two techniques. The classical Raji assay using I125 anti Ig and a modification of this technique using FITC-anti Ig. The latter method detects immune complexes by fluorescence using flow cytometry. Components within immune complexes have been separated and analyzed by gel electrophoresis. In addition, immune complex isolation and Western blotting techniques are being applied to detect viral antigens within the complexes of patients with AIDS disease as well as other diseases. The mechanisms by which immune complexes regulate immune responses are also being examined along with interactions at the cell surface between complement components and membrane components. Antigen-excess complexes and antibody-excess complexes are being constructed and used to study their regulatory influences on immune functions. The involvement of idiotypy in the generation of immune complexes will also be investigated.